Objective. To evaluate the incidence of post-embolization syndrome (PES) and the effect of venoactive therapy on its development, severity, and duration after endovascular embolization of gonadal veins (EEGV) with coils in patients with pelvic congestion syndrome (PCS). Materials and Methods. We analyzed the outcomes of EEGV with coils in 70 female patients who received (n = 38; group 1) or did not receive (n = 32; group 2) treatment with a venoactive drug (VAD) before and after the procedure. Assessments of the EEGV efficacy and for possible signs of PES were done on days 1, 5, 10, 15, 20, and 30 after the intervention. All patients underwent transvaginal and transabdominal duplex ultrasound scanning (DUS) after EEGV. In addition, patients with PES were examined using the computed tomography of the pelvic veins in the postprocedural period. Results. Technical success of EEGV was achieved in 100% of patients. Pelvic venous pain (PVP) reduction after EEGV was observed in 77.1% of patients. The PES was diagnosed in 18.6% of cases (10.5% in group 1 vs. 28.1% in group 2, p > 0.05). In three patients of group 1, the protrusion of coils was suspected and eventually verified during the resection of the left gonadal vein with coils. The group 1 patients had less severe post-embolization pain (6.2 ± 0.4 vs. 7.8 ± 0.3 scores in group 2; p = 0.009) and three times shorter duration of PES (5.0 ± 1.2 vs. 16.2 ± 2.7 days; p = 0.003). No significant differences in the diameters of gonadal veins, side of embolization, and number of coils were revealed between patients with and without PES. The rate of parametrium vein thrombosis was found to be significantly higher in patients with PES than in those without PES (30.7% vs. 18.5%, respectively; p < 0.05). Conclusion. The PES is a frequent complication of EEGV with coils and occurs in 18.6% of patients. Venoactive treatment does not effect the incidence of this complication but reduces the PES severity and duration.